Warbird Information Exchange

I seem to be a bit brain-dead today...

Can anyone remind me what the rearward-facing vent on the underside of the outboard engine cowlings on B-17Gs is for please?
It's the one just forward of the two supercharger cooling air intake scoops, and I can't seem to find it in the IPL or E&M manuals.

See here for the one I mean: http://www.flickr.com/photos/astaken/2870067375/

All the best,
PB

_________________
Paul Bellamy

401BG Association Historian & Honorary Life Member
401BG Historical Society (UK) Member
1st Air Division HQ Historical Society (UK) Founder Member
Director of Archives & Collections, Airfield Research Group Archive, Alconbury
RAF Alconbury Base Historian

It is actually a vent that allows some of the radiated exhaust heat to escape.
For the same outboard positions, in front of main exhaust bottom branch on some B-17s, is a 'ram air' forced vent ensuring some additional cooling air is run into the exhaust channel which needs to then escape rather than end up in a 'dead end', which this vent allows to happen.
It is of course a different arrangement altogether for the inboard exhausts.

Ta for that BB.

All the best,
PB

_________________
Paul Bellamy

401BG Association Historian & Honorary Life Member
401BG Historical Society (UK) Member
1st Air Division HQ Historical Society (UK) Founder Member
Director of Archives & Collections, Airfield Research Group Archive, Alconbury
RAF Alconbury Base Historian